Related Party Transactions (Brightstar) (Details) - Successor [Member] - Brightstar [Member] - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Related Party Transaction [Line Items]
Accounts receivable		$ 197	$ 430
Accounts payable		96	96
Revenue from related parties	[1]	1,731	1,818
Related party costs	[1]	$ 1,743	$ 1,887

[1] (1)Amounts for all other reported periods were immaterial.